The invention relates to a tire valve, in particular a gas and/or pneumatic tire valve, comprising a valve body which penetrates a bore in a rim, in particular a vehicle rim, embodies a lower valve body portion disposed on one side of the rim, in particular in the interior of the rim, in the mounted state as well as an upper valve body portion protruding from the rim bore, and is configured so as to cooperate with a cap nut in the region of the upper valve body portion. The invention further relates to a valve system and a tire.
Various approaches are known in the art for producing, to prevent loss of air, a seal between a pneumatic tire valve and the valve bore (referred to hereinafter also as the rim bore) surrounding said pneumatic tire valve in the pneumatic tire rim. On the one hand there are what are known as shoulder or flat seals such as, for example, in DE 28 13 742. On the other hand O-ring seals are used.
However, both solutions are, viewed per se, technically disadvantageous: A shoulder or flat seal, which typically consists of a flat rubber ring and is optionally provided with a shoulder portion, places relatively low demands on the flatness of the bearing surface (i.e. the external flat edge portion of the rim bore) and on the hole tolerances of this rim bore, as the large rubber volume of seals of this type easily compensates for deviations. A drawback however is that during the fitting of valves comprising seals of this type, (low) torque limits may not be exceeded: this would lead to the destruction of the seal. As, in addition, the sealing elements become deformed under pressure, very low loosening moments for the cap nut fastening the valve are generally and disadvantageously obtained.
The known O-ring seals, on the other hand, allow very much higher tightening moments, as the cap nut acts directly on the edge portion of the rim bore and metal-to-metal contact thus exists; advantageously, accordingly high loosening moments can be achieved for the fastening cap nut. On the other hand, it is disadvantageous that an O-ring seal of this type places very high demands on the flatness of the bearing surface in the rim bore edge region and on the bore tolerances themselves, so that in some cases considerable additional costs for production and assembly are necessary in this case.
According to DE 20 2004 020 121 U1, the aforementioned drawbacks are eliminated by a tire valve in which the lower valve body portion forms an annular shoulder which offers an abutment for a flat edge portion of the rim bore, into which an annular groove, which is open toward the edge portion, is shaped and in which the edge portion can be braced by tightening the cap nut. In addition, a specific molded seal is provided for sealing the rim bore. According to this solution, the molded seal is provided to be inserted into the annular shoulder. Although the tire valve proposed in this form allows, through the annular shoulder, the pressing of the valve seal to be limited, it has, as a result of the annular shoulder with the inner valve seal, a comparatively large maximum diameter. As a result, the tire valve proves to be comparatively large for certain applications. In particular, it has been found that the maximum diameter of a tire valve of this type proves in many cases to be too large for a radius of transition from a well base to the dropped center of a rim. A tire valve of the type mentioned at the outset is described in DE 103 14 783 A1 but is still capable of improvement.